Chiral tilted smectic liquid-crystalline phases having ferroelectric properties can be prepared by adding a suitable chiral dope to base mixtures having one or more tilted smectic phases (L. A. Beresnev et al., Mol. Cryst. Liq. Cryst. 89, 327 (1982); H. R. Brand et al., J. Physique 44 (lett.), L 771 (1983). Phases of this type can be used as dielectrics for fast-switching displays based on the principle of SSFLC technology described by Clark and Lagerwall (N. A. Clark and S. T. Lagerwall, Appl. Phys. Lett. 36, 899 (1980); U.S. Pat. No. 4,367,924) on the basis of the ferroelectric properties of the chirally [sic] tilted phase. The elongate molecules in this phase are arranged in layers, the molecules having a tilt angle to the layer normals. On moving from layer to layer, the tilt direction changes by a small angle with respect to an axis perpendicular to the layers, so that a helical structure is formed. In displays based on the principle of SSFLC technology, the smectic layers are arranged perpendicular to the plates of the cell. The helical arrangement of the tilt directions of the molecules is suppressed by a very small separation of the plates (about 1-2 .mu.m). This forces the longitudinal axes of the molecules to line up in a plane parallel to the plates of the cell, which causes two preferential tilt alignments to be formed. Application of a suitable alternating electrical field allows switching back and forth between these two states in the liquid-crystalline phase having spontaneous polarization. This switching operation is significantly faster than in conventional twisted cells (TN-LCDs), which are based on nematic liquid crystals.
The currently available materials having chirally [sic] tilted smectic phases (such as, for example, Sc* [sic ], but also S.sub.H *, S.sub.I *, S.sub.J *, S.sub.K *, S.sub.G * and S.sub.F *) has the great disadvantage for many applications of low chemical, thermal and photostability. A further disadvantageous property of displays based on currently available chirally [sic] tilted smectic mixtures is that the spontaneous polarization has values which are too low, so that the response time behavior of the displays is adversely affected and/or the pitch and/or the tilt and/or the viscosity of the phases does not meet the requirements of display technology. In addition, the temperature range of the ferroelectric phases is usually too small and is predominantly at excessively high temperatures.